Create the HTML output and two style sheets. The ODS HTML statements opens the HTML destination and creates HTML output. The STYLESHEET= option places the style information for the HTML output into two external files. The URL= suboption specifies a URL for the two files, File1.css and File2.css. ODS uses these URLs (instead of the filename) in all the links and references that it creates and that point to those files.

ods html body='StylesheetExample.html'
   stylesheet=(url='/css/file1.css /css/file2.css');